Could be a firewall issue. This happens to me if I try to side load within the Samsung Network Trr SDBoverBT
Connect your phone to your computer.
Allow Data Access
On the phone make sure USB debugging is enabled in the Developer Options
From the \program files\Galaxy Watch Designer\Tizen\Tools
copy sdboverbt_160523.apk to your phone and install it.
Make sure debugging is enable for both your watch and phone
On the phone enable USB debugging in the developer Options
Launch SDBoverBT on your phone
It will ask you to select your device it will show your watch click on it and it will be connected
You may have to agree to the RSA encryption or some other permission the first time and it doesn’t show very long so be sure you have your watch handy and running when you do that. same thing for when you connect phone to computer it may ask it may not.
Once you are connected plug your phone into your computer and allow data transfer on your phone
launch GWD and from your project chose run on device
It will start the scan and then it will show the SDBoverBT icon
You may have to agree to another permission on my watch one more time.
If that works then it is either a WiFi issue or Firewall.
Samsung Developer Program